Cognitive Development

All 17 Terms & Definitions

Schema (Piaget)

A mental framework or cognitive structure that organises and interprets information. Schemas begin as simple sensorimotor patterns (sucking, grasping) and develop into increasingly abstract mental representations. All cognitive development, for Piaget, involves schemas being built, refined, and reorganised.

Assimilation (Piaget)

The process of interpreting new experiences through existing schemas — fitting the world into what you already know. A child who calls all four-legged animals 'dog' is assimilating new animals into their existing dog schema.

Accommodation (Piaget)

The process of modifying or creating new schemas when existing ones cannot adequately assimilate new information. The child who encounters a horse and revises their schema to distinguish horses from dogs is accommodating.

Equilibration (Piaget)

Piaget's proposed mechanism driving cognitive development. When assimilation and accommodation are in balance, the child is in cognitive equilibrium. Encountering information that doesn't fit existing schemas creates disequilibrium — a motivating state that prompts accommodation and advances development.

Object permanence (Piaget)

The understanding that objects continue to exist even when not visible, audible, or otherwise perceptible. According to Piaget, this emerges fully during the sensorimotor stage (8–12 months). Research by Baillargeon suggests rudimentary object permanence may be present much earlier.

Conservation (Piaget)

The understanding that quantity, number, mass, or volume remains the same despite changes in form or arrangement. Piaget's classic task: children in the preoperational stage judge that a tall, thin glass holds more water than a short, wide glass after watching the same water poured from one to the other.

Zone of Proximal Development — ZPD (Vygotsky)

Vygotsky's concept describing the distance between what a learner can achieve independently and what they can achieve with the guidance of a more knowledgeable other. The ZPD is the ideal target for instruction — challenging enough to require support, achievable enough to succeed with it.

Scaffolding (Vygotsky)

Temporary, adjustable support provided by a more knowledgeable other that allows a learner to perform a task within their ZPD. As competence develops, support is progressively withdrawn. The term was introduced by Wood, Bruner, and Ross (1976), inspired by Vygotsky's theory.

More Knowledgeable Other — MKO (Vygotsky)

Vygotsky's term for anyone with a higher level of understanding than the learner — a parent, teacher, peer, or even a book. The MKO provides the social mediation that Vygotsky placed at the heart of cognitive development.

Egocentrism (Piaget)

The preoperational child's inability to take another person's perspective — to understand that others may see, know, or feel things differently from themselves. Illustrated by Piaget's three mountains task, in which children typically assume another person sees the same view of a model as they do. Not to be confused with selfishness; it is a cognitive limitation, not a moral one.

Centration (Piaget)

The preoperational child's tendency to focus on only one feature of a problem at a time, neglecting other relevant dimensions. Central to failures on conservation tasks: the child centres on the height of a glass and ignores its width, leading to the erroneous conclusion that a taller glass contains more liquid.

Private speech (Vygotsky)

The self-directed talk children produce while working on tasks — talking themselves through a problem aloud. Piaget interpreted this as evidence of cognitive immaturity (egocentric speech). Vygotsky's interpretation was opposite: private speech is a transitional cognitive tool being internalised. Research by Berk (1986) supports Vygotsky — private speech peaks on difficult tasks and decreases as competence increases, not as social cognition matures.

Inner speech (Vygotsky)

Vygotsky's term for the fully internalised, condensed form of private speech — thinking in words, without external vocalisation. Inner speech is the endpoint of a developmental process: external social speech → private speech → inner speech. For Vygotsky, inner speech is the primary medium of higher mental functioning.

Violation-of-expectation (VOE) paradigm

A behavioural method developed to probe infant cognition without requiring motor responses. Infants are habituated to a possible event, then shown either that same event or an impossible one (e.g. a toy car passing through a solid barrier). If infants look significantly longer at the impossible event, this is taken as evidence that they expected the possible outcome — and therefore possess the underlying knowledge. Used by Baillargeon to demonstrate object permanence far earlier than Piaget's sensorimotor account predicts.

Habituation and looking time

Habituation is the decrease in a response (such as looking) that occurs as a stimulus becomes familiar. In infant research, habituation–dishabituation procedures exploit looking time as a non-verbal index of knowledge and expectation. Infants look longer at novel or unexpected events; measuring how long they look allows researchers to infer what they know without requiring active motor responses.

Competence–performance distinction

The distinction between what a child actually knows (competence) and what they can demonstrate on a given task (performance). Baillargeon argued that Piaget's tasks systematically underestimated infant competence because they required motor responses that infants lack. The A-not-B error, for instance, reflects executive control immaturity — not the absence of object permanence. VOE methods separate competence from performance by using looking rather than reaching.

Core knowledge (Baillargeon)

The hypothesis that infants are born with — or develop very early — domain-specific systems of knowledge about the physical world (objects, agents, number, space). Baillargeon's research showing object permanence in young infants is foundational evidence: much of what Piaget attributed to construction through sensorimotor action appears to be available far earlier, suggesting initial knowledge systems rather than blank-slate construction.